3. Other names for S- waves are secondary waves, shear waves, and sometimes elastic S-waves. Other names for P-waves are primary waves and compressional waves.
4. You need 3 stations, because scientists find the difference between the arrival times of the primary and the secondary waves at each of the 3 stations, then the time difference is used to determine the distance of the epicentre from each station. The greater the difference in time, the further away the epicentre is. A circle is drawn around each station, with a radius corresponding to the epicentre’s distance from that station. The point where the three circles meet is the epicentre. If you only had two stations, you could only predict the epicentre, as the point where all three circles meet wouldn’t be complete, you’d have to try and estimate where the third one would intercept. This would greaten the chance of error and isn’t as accurate.
Hope this helps!
Answer with Explanation:
A "chemical change" occurs when the structure of the molecules change. If there's no change in structure, it is called a "physical change." This also means that a <em>chemical reaction </em>has to occur for something to be considered a chemical change.
Gasoline when used as a fuel is being transformed into other forms of energy. It undergoes a process called <em>"combustion."</em>
When used as a fuel for cars, <em>the gasoline is being burned to produce </em><u><em>heat energy.</em></u> This energy is then converted into <u><em>mechanical energy</em></u> that allows the car to move. Clearly, the gasoline has undergone a chemical change.
Barium chloride + sodium sulphate --> barium sulphate + sodium chloride
BaCl2 + Na2SO4 ---> BaSO4 + 2 NaCl
The barium sulphate appears as a white precipitate
Silver nitrate + Sodium chloride ---> Silver Chloride + sodium nitrate
AgNO3 + NaCl ----> AgCl + NaNO3
The silver chloride appears as a white precipitate.
These are sometimes called double decomposition reactions.
The answer is B) particles move faster.
